Circuit Description

DTCs P1300 through P1315 Ignition Coil Primary Feedback Circuit, monitors the primary circuitry of individual ignition coils for successful completion of an ignition event. The ignition trigger signal and ignition fail-safe input signal provide crucial information in control of ignition system timing and activation of fail-safe function. Based on initial timing angle, calculated from crankshaft and the camshaft position signals, Powertrain Control Module (PCM) calculates the ignition trigger signal. Ignition trigger signal is then sent to the ignition control circuitry located in each ignition coil. Ignition control circuitry initiates ignition dwell period by commanding the power transistor ON. When PCM determines the proper time to provide spark, the PCM turns OFF ignition trigger signal. In response to PCM signal, the ignition coil control circuitry turns OFF power transistor, producing a high voltage discharge from secondary coil windings. After spark has occurred, the control circuitry sends an ignition fail-safe input signal back to the PCM, confirming that an ignition event has taken place. If ignition fail-safe input signal is not received by the PCM, a cylinder specific DTC will set.

Anytime the fail-safe input signal is lost, engine operation will enter fail-safe function. If engine load exceeds certain parameters during fail-safe function, FUEL CUT-OFF mode is activated and fuel injector operation is ceased. The suspension of fuel injection in FUEL CUT-OFF mode protects the catalytic converter from damage. Damage can occur when excess unburned fuel reaches the converter and causes the catalyst to overheat.